Gem::Commands::UnpackCommand#description

# File tmp/rubies/ruby-3.1.3/lib/rubygems/commands/unpack_command.rb, line 47
  def description
    <<-EOF
The unpack command allows you to examine the contents of a gem or modify
them to help diagnose a bug.

You can add the contents of the unpacked gem to the load path using the
RUBYLIB environment variable or -I:

  $ gem unpack my_gem
  Unpacked gem: '.../my_gem-1.0'
  [edit my_gem-1.0/lib/my_gem.rb]
  $ ruby -Imy_gem-1.0/lib -S other_program

You can repackage an unpacked gem using the build command.  See the build
command help for an example.
    EOF
  end